Preparation of hair treating compositions in solid form



United States Patent PREPARATION OF HAIR TREATING COMPOSI- TIONS IN SOLID FORM Lionel Leslie Frederick Deadman, Leatherhead, England, assignor to Ashe Laboratories Limited, Leatherhead, England No Drawing. Application September 12, 1952, Serial No. 309,354

This invention is for improvements in or relating to hair-treating preparations and is especially, though not exclusively, concerned with. the preparation of materials used in the so-called cold permanent waving of hair, particularly human hair.

In one known method of waving hair by the cold permanent waving process, a mercaptan is dissolved in water, the pH adjusted to a suitable value, and the resulting solution applied to the hair in order to soften or relax the hair and therefore to condition the hair for change in configuration. Examples of mercaptans which may be used in this process as well as the over-all process are described, for example, in British patent specification No. 589,956. The treated hair is manipulated to a desired configuration, which if desired is then set by treating the; hair with a solution of an oxidising agent such as potassium bromate.

It is an object of this invention to provide a new and convenient form of presentation of mercaptans suitable for use in cold hair waving operations. More particularly the invention provides a relatively simple and economic process for the manufacture of a powder containing a mercaptan which when dissolved in water will have satisfactory hair-relaxing properties. The advantages of the use of a powder compared with a solution are:

(a) the bulk can be considerably reduced with consequent saving in storage space;

(b) the active material is in a concentrated form, which is desirable from the point of view of transport costs;

(c) a powder may be dissolved in varying amounts of water to suit difierent types of hair; and

(d) the material may be packed in envelopes of paper or other material instead of bottles, with considerable saving in packing cost.

Research on the problem of preparing a suitable powder from the mercaptans of choice viz: those which also contain carboxyl groups, such as thioglycollic acid, has revealed a number of difiiculties to be overcome if success is to be achieved. In particular it has proved difficult for a variety of reasons to prepare such a powder which is reasonably stable on storage and which when dissolved in water will give and maintain the pH required for satisfactory waving viz: of approximately 9.2. For example, under ordinary manufacturing conditions neutralisation of thioglycollic acid directly with a suitable alkali to produce a powder, may generate sufficient heat to cause partial decomposition of the thioglycollic acid or its salt. Again, those alkalis which may not cause heat to be liberated are generally not of themselves sufficiently strongly basic to ensure a pH of approximately 9.2 when the required amount of the powder is subsequently dissolved in water.

According to the present invention,

a process for preparing a solid composition containing a derivative of a mercapto carboxylic acid suitable on dissolution in water to form a hair-relaxing solution, comprises neutralising a ice mercapto carboxylic acid with solid ammonium carbonate or bicarbonate, or a solid mixture of these, and in corporating either simultaneously or subsequently a proportion of a solid alkaliwhich is substantially more basic than the said ammonium salts.

It is a surprising fact that the reaction between a mercapto carboxylic acid, especially thioglycollic acid, and the said ammonium salts is endothermic. In the process of the present invention this phenomenon is utilised for the purpose of preventing thermal decomposition of the acid While at the same time obtaining a powder which, when dissolved in water, will give the appropriate pH.

The proportion of stronger alkali will vary according to the precise conditions of the process and with the properties of the stronger alkali. As will be evident, the precise quantity to be employed in any particular case can readily be determined by simple preliminary trial, regard being had to the following criteria and to the examples hereinafter given.

The stronger alkali has two functions: Firstly, it must be sufficiently strongly basic and be present in a sufiicient quantity to ensure that a pH of 9.0-9.5 is obtained when the powder prepared by the method described below is subsequently dissolved in water. Secondly, it must be in sufiicient quantity to absorb any water liberated in the formation of the ammonium salt, thus ensuring a relatively free-flowing powder.

The solid (stronger) alkali is preferably a suitable sodium or potassium compound for example, the carbonates and tri-metal phosphates. Preferably, such strongly basic substances as the metal hydroxides are avoided since, in significant quantity, they give when dissolved in water a pH higher than the permissible maximum.

in carrying the process of the present invention into effect, it is preferred to add the ammonium salt and the stronger alkali simultaneously to the mercapto carboxylic acid. The two alkaline substances compete for reaction with the acid and the relative proportions of the two alkaline substances i such that the endothermic reaction of the ammonium salt and the exothermic reaction of the stronger alkali proceed simultaneously without an excessive rise in temperature such as to bring about any substantial thermal decomposition.

The process of the present invention is illustrated by the following examples:

Example I Gm. Thioglycollic acid 20 Commercial ammonium carbonate (powdered) 20 Sodium carbonate 24 The thioglycollic acid and ammonium carbonate are stirred together until no more carbon dioxide is liberated. The sodium carbonate is then added and the whole stirred until a dry, free-flowing powder is obtained.

A suitable solution for use in cold permanent waving may be obtained by dissolving 15 gm. of the powder in ml. of Water.

Example 11 Gm. Thioglycollic acid (95%) 20 Ammonium bicarbonate l6 Trisodium phosphate 45 The ammonium bicarbonate and trisodium phosphate powders are mixed together and added all at once to the thioglycollic acid, and the whole stirred till a dry, freeflowing powder is obtained.

A solution suitable for cold permanent waving may be prepared by dissolving 20 gm. of the powder in 100 ml. of water.

The powders of the present invention when dissolved in water may also be employed in conjunction with suitable water-soluble dyestuffs, preferably coal-tar dyestuffs, in the process of dyeing hair described in specification No. 267,193 with or without simultaneous waving of the hair.

It is to be understood that where the term ammonium carbonate is used in this specification it may also include commercial ammonium carbonate, which is us ually a mixture of ammonium bicarbonate and ammonium carbamate.

I claim:

1. A process for preparing a solid composition containing a derivative of a mercapto carboxylic acid suitable on dissolution in water to form a hair-relaxing solution which comprises neutralising a mercapto carboxylic acid with a member of the class consisting of solid ammonium carbonate, solid ammonium bicarbonate and a solid mixture of these two salts, and incorporating a solid alkali which is substantially more basic than the said ammonium salt in sufiicient quantity to absorb any water formed in the reaction and to bring the composition to an acidity such that an aqueous solution of it has a pH of 9.0 to 9.5.

2. A process for preparing a solid composition containing a derivative of a mercapto carboxylic acid suitable on dissolution in water to form a hair-relaxing solution which comprises neutralising a mercapto carboxylic acid with a member of the class consisting of solid ammonium carbonate, solid ammonium bicarbonate and a solid mixture of these two salts, and simultaneously incorporating a solid alkali which is substantially more basic than the said ammonium salt. in sufficient quantity to absorb any water formed in the reaction and to bring the composition to an acidity such that an aqueous solution of it has a pH of 9.0 to 9.5.

3. A process for preparing a solid composition containing a derivative of a mercapto carboxylic acid suitable on dissolution in water to form a hair-relaxing solution which comprises neutralising a mercapto carboxylic acid with a member of the class consisting of solid ammonium carbonate, solid ammonium bicarbonate and a solid mixture of these two salts, and subsequently incorporating a solid alkali which is substantially more basic than the said ammonium salt. in sufiicient quantity to absorb any water formed in the reaction and to bring the composition to an acidity such that an aqueous solution of it has a pH of 9.0 to 9.5.

4. A process according to claim 1 wherein said more basic solid alkali is a compound of sodium.

5. A process as claimed in claim 1 wherein the said more basic solid alkali is selected from the group consisting of sodium carbonate and tri-sodiurn phosphate.

6. A process as claimed in claim 2 in which the ammonium compound i commercial ammonium carbonate.

7. A process as claimed in claim 1 wherein the mercapto carboxylic acid is thioglycollic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,506,492 DeMytt May 2, 1950 2,631,965 Schnell Mar. 17, 1953 2,633,447 Head Mar. 31, 1953 2,653,121 Schnell Sept. 22, 1953 2,708,940 DeMytt May 24, 1955 FOREIGN PATENTS 469,379 Italy Feb. 26, 1952 

1. A PROCESS FOR PREPARING A SOLID COMPOSITION CONTAINING A DERIVATIVE OF A MERCAPTO CARBOXYLIC ACID SUITABLE ON DISSOLUTION IN WATER TO FORM A HAIR-RELAXING SOLUTION WHICH COMPRISES NEUTRALISING A MERCAPTO CARBOXYLIC ACID WITH A MEMBER OF THE CLASS CONSISTING OF SOLID AMMONIUM CARBONATE, SOLID AMMONIUM BICARBONATE AND A SOLID MIXTURE OF THESE TWO SALTS, AND INCORPORATING A SOLID ALKALI WHICH IS SUBSTANTIALLY MORE BASIS THAN THE SAID AMMONIUM SALT IN SUFFICIENT QUANTITY TO ABSORB ANY WATER FORMED IN THE REACTION AND TO BRING THE COMPOSITION TO AN ACIDITY SUCH THAT AN AQUEOUS SOLUTION OF IT HAS A PH OF 9.0 TO 9.5. 